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From: gary@APLPY.ARPA.UUCP
Newsgroups: comp.lang.ada
Subject: Re:  VAX Ada sequential IO and Direct IO
Message-ID: <8704140117.AA13151@aplpy.arpa>
Date: Mon, 13-Apr-87 20:17:39 EST
Article-I.D.: aplpy.8704140117.AA13151
Posted: Mon Apr 13 20:17:39 1987
Date-Received: Wed, 15-Apr-87 04:37:01 EST
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> Has anyone had problems with VAX Ada sequential_io and direct_IO when
> instantiated with a discriminated record type which has an unconstrained
> component.  I keep getting use_error raised when doing a create or open.
> 
> example
> 
> 
> type foo(a : integer) is
> 	record
> 	   f1 : string(1..a);
> 	end record;
> 
> even if I restrict the range of 'a' by using a subtype of integer, or
> create an integer type with a restricted range I still get a use_error.
> In addition to the use error, an RMS error is listed as max record size 
> exceeded.
> 
> 	... Tony Alden
> 	(TRW)
> 
> 
We've been able to use sequential and direct io with discrimant
records successfully by specifying a default discriminant value,
i.e. the records have to be "constrained" at time of
instantiation of io package.

	You might try something like the following:

  type foo(a : integer := MAXLENGTH) is
  	record
  	   f1 : string(1..a);
  	end record;
  
  package rec_io is new sequential_io(foo);


	Good Luck,

				Gary Gafke
				gary@aplpy.arpa
			or	seismo!mimsy!aplcen!gary
			or	(301) 953-6999